The stronger the signal the closer you are, and from experience some can be REALLY hard to find.
Distress signals:
Follow the bip's, and you should sometimes see a percentage number displayed in upper left corner, on how close you are. The closer you get, the higher percentage, and faster bip's. Change direction accordingly if the percentages drops (finding correct course again)
Level of enemies: You don't. Except that a skull means they are several levels above you.
1) The signals will gain strength (become louder and clearer) as you approach the source. It's usually not that far. When you get close enough to get a clear signal the broadcast itself will usually include clues.
2) Be careful of anything with a Skull next to its' name. That indicates a much higher level opponent than you. Other than that, pay attention to the Gear they are using. If they have Power Armor and Gatling Lasers, then they are high level. If they have no armor and a stick they are low level.
Move in one direction and see if it gets weaker or stronger. That's all there is to it.
Helps to wear headphones when tracking down radio signals, by the way.
This is something that would make useful perk. Maybe a visual representation, compass pip, or map marker. It would make much more sense having this as a perception perk than something like refractor. How is energy resistance a perception perk anyway?
As said by others, head to where they get clearer.
An important additional point, though, is that they are often behind bunker doors - which are, in and of themselves, behind other obstacles. Especially bushes, but sometimes rocks and rad barrels. So a cursory glance is not sufficient; you need to really comb the area. If anything, make beelines for bush obstacles, because Bethesda looooves to hide the doors there.
Orrrr you could just use the Fallout wiki, which has documented all the radio stations, distress included. They players there have provided detailed instructions.
As others have indicated the signal strength gets stronger or weaker when you move, In the upper left hand corner of the screen, a numeric representation of the signal strength will periodically display as you move (it isn't an constant display, it will appear and then disappear.)
As for determining the level of hostile creatures without the perception perk, you cannot tell exactly, but if they are well above you in level, they will have a skull displayed next to their name.
Pertaining to dumb questions. my Drill Sergeant always insisted that the only dumb question was the one that isn't asked. However, this did not stop him from calling me a moron whenever I asked a question, and then proceed to order me to push the ground another two feet closer to sea level.
Depends on the radio signal. If you hear beeping, use the numeric representation and if the beeps get shorter. If you are talking about radio signals that are available after activating relay stations, then either use a guide like Fallout wiki or hopefully the radio message gives a location. Then use your local map to look for any entrances. Sadly, this is one of the very few times that the local map is of any use.
Well, for emergency signals, in the top left of my screen a notification pops up like every 15 seconds, that gives me signal strength in % but i usually don't pay attention to that I usually just pay attention to the noise, it gets louder and faster the closer you get
You can get the Awareness perk if you want to know the level, damage resistance, energy resistance, radiation resistance, and poison resistance of your enemies (lower numbers are better). It requires a Perception of 3.
As said, the louder and clearer the signal gets, the closer you are to its location. A lot of the are fairly well hidden so make sure to listen to what is being said on the signal and look in more obscure places.
As for knowing enemy level, I'd say all you need to know is when the enemy is a higher level than you, which is indicated by a red skull that appears next to their name if that is the case. No reason to know their level otherwise unless you have any interest in the Intimidation perk or something similar.
Eat a Salisbury Steak when you find the signal, I've found it increases perception and helps you locate the signal faster
The level of many enemies is indicated by their name.
For instance supermutants, gunners and so on come in different ranks.
After a while you become familiar with them.
Same with Deathclaws and other creatures.
The stronger variants have have different additions to their name.
For instance if you see glowing in the name you know it will give you extra radiation damage.
If you see a radscorpion you know they can be a tough competitor.
If you see a Radscorpion that is called the Deathskull Radscorpion you know it will be the toughest of radscorpions.
And there are other variants in between.
predators, stalkers, hunters albino and so on.
I have a problem with this. They are often so mumbled, I can't pick up what they are saying, especially so as a non-native speaker. I have to jank all my volumes up to even stand a chance Would have been nice if there was subtitles to these radio messages which leads to quests. Not only for non-native speakers, but also for those who are deaf